The genetic capacity of Borrelia burgdorferi appears to reside in a collection of linear and circular, double stranded DNA molecules ranging from a few to a thousand kilobases in length. Although much variability in DNA profile has been noted among isolates from around the world and as a consequence of passage in the laboratory, important genes have been localized to both linear and circular molecules. The genomes of bacteria of the genus Borrelia are distinct from those of most bacteria in that the chromosome and some of the plasmids are linear DNA molecules. Furthermore, it has been shown that the ends of the linear plasmids, are covalently closed. Previously, however, the termini of the chromosome of B. burgdorferi, were uncharacterized. Termini from B. burgdorferi strain B31-4, a strain which does not contain linear plasmids, were purified and characterized and determined to have physical properties similar to typical eukaryotic telomeres. While biologically significant concentrations of Aphidicolin, Ara C, cis Platinum, CPX, Hydroxyurea, Mimosine, Nalidixic Acid, Trioxsalen and Boromethyglycine showed little effect on growth when added to BSK II cultures, melittin, a 26 amino acid peptide contained in honeybee venom, showed immediate and profound inhibitory effects when monitored by dark-field microscopy, by field emission scanning electron microscopy and by optical density measurements. Furthermore, at melittin concentrations as low as 100 :g/ml, virtually all spirochete motility ceased within seconds of inhibitor addition. Ultrastructural examination of these spirochetes revealed obvious alterations in the surface envelope of the spirochetes.